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Colistin Interaction and Surface Changes Associated with mcr-1 Conferred Plasmid Mediated Resistance in E. coli and A. veronii Strains. Pharmaceutics 2022; 14:pharmaceutics14020295. [PMID: 35214028 PMCID: PMC8880236 DOI: 10.3390/pharmaceutics14020295] [Citation(s) in RCA: 10] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/30/2021] [Revised: 01/02/2022] [Accepted: 01/16/2022] [Indexed: 02/05/2023] Open
Abstract
Colistin, a polycationic antimicrobial peptide, is one of the last-resort antibiotics for treating infections caused by carbapenem-resistant Gram-negative bacteria. The antibacterial activity of colistin occurs through electrostatic interaction between the polycationic peptide group of colistin and the negatively charged phosphate groups of lipid A membrane. This study investigated the interaction of colistin with the outer membrane and surface constituents of resistant and susceptible strains of Escherichia coli and Aeromonas veronii harboring mcr-1 resistance gene. Bacterial membrane and lipopolysaccharide used in this study were isolated from susceptible as well as colistin-resistant strains of E. coli and A. veronii. Interaction of colistin with the bacterial surface was studied by deoxycholate and lysozyme sensitivity test, N-phenyl-1-naphthylamine (NPN) uptake assay, Atomic force microscopy (AFM), Zeta potential measurements and 1H NMR. The binding affinity of colistin was found to be lower with outer membrane from resistant strains in comparison with the susceptible strains. Colistin exposure enhances the outer membrane permeability of the susceptible strains to deoxycholate and lysozyme. However, on the other hand, colistin dose of 256 µg/mL did not permeabilize the outer membrane of resistant bacteria. The NPN permeability in resistant strains was greater in comparison with susceptible strains. Atomic force microscopy images depicted smooth, featherless and deformed membranes in treated susceptible cells. Contrary to the above, resistant treated cells displayed surface roughness topography even at 256 µg/mL colistin concentration. Surface charge alterations were confirmed by Zeta potential measurements as a function of the growth phase. Mid-logarithmic phase susceptible strains showed a greater negative charge than resistant strains upon exposure to colistin. However, there was no statistical variation in the Zeta potential measurements between resistant and susceptible strains at the stationary phase. NMR analysis revealed line broadening in susceptible strains with increasing colistin: LPS aggregates mass ratio. Moreover, resistant strains did not show line broadening for the outer membrane, even at the highest mass ratio. The findings of this study suggest that the resistant strains of E. coli and A. veronii can block the electrostatic contact between the cationic peptide and anionic lipid A component that drives the first phase of colistin action, thereby preventing hydrophobically driven second-tier action of colistin on the outer lipopolysaccharide layer.
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Escobar‐Salom M, Torrens G, Jordana‐Lluch E, Oliver A, Juan C. Mammals' humoral immune proteins and peptides targeting the bacterial envelope: from natural protection to therapeutic applications against multidrug‐resistant
Gram
‐negatives. Biol Rev Camb Philos Soc 2022; 97:1005-1037. [PMID: 35043558 PMCID: PMC9304279 DOI: 10.1111/brv.12830] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2021] [Revised: 12/12/2021] [Accepted: 12/15/2021] [Indexed: 12/11/2022]
Abstract
Mammalian innate immunity employs several humoral ‘weapons’ that target the bacterial envelope. The threats posed by the multidrug‐resistant ‘ESKAPE’ Gram‐negative pathogens (Klebsiella pneumoniae, Acinetobacter baumannii, Pseudomonas aeruginosa, and Enterobacter spp.) are forcing researchers to explore new therapeutic options, including the use of these immune elements. Here we review bacterial envelope‐targeting (peptidoglycan and/or membrane‐targeting) proteins/peptides of the mammalian immune system that are most likely to have therapeutic applications. Firstly we discuss their general features and protective activity against ESKAPE Gram‐negatives in the host. We then gather, integrate, and discuss recent research on experimental therapeutics harnessing their bactericidal power, based on their exogenous administration and also on the discovery of bacterial and/or host targets that improve the performance of this endogenous immunity, as a novel therapeutic concept. We identify weak points and knowledge gaps in current research in this field and suggest areas for future work to obtain successful envelope‐targeting therapeutic options to tackle the challenge of antimicrobial resistance.
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Affiliation(s)
- María Escobar‐Salom
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Gabriel Torrens
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Elena Jordana‐Lluch
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Antonio Oliver
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
| | - Carlos Juan
- Department of Microbiology University Hospital Son Espases‐Health Research Institute of the Balearic Islands (IdISBa) Carretera de Valldemossa 79 Palma Balearic Islands 07010 Spain
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Agyeman AA, Rogers KE, Tait JR, Bergen PJ, Kirkpatrick CM, Wallis SC, Bulitta JB, Paterson DL, Lipman J, Nation RL, Roberts JA, Landersdorfer CB. Evaluation of Meropenem‐Ciprofloxacin Combination Dosage Regimens for the Pharmacokinetics of Critically Ill Patients With Augmented Renal Clearance. Clin Pharmacol Ther 2021; 109:1104-1115. [DOI: 10.1002/cpt.2191] [Citation(s) in RCA: 10] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2020] [Accepted: 01/19/2021] [Indexed: 12/11/2022]
Affiliation(s)
- Akosua A. Agyeman
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Kate E. Rogers
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Jessica R. Tait
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Phillip J. Bergen
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Carl M. Kirkpatrick
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
| | - Steven C. Wallis
- The University of Queensland Centre for Clinical Research Royal Brisbane and Women’s Hospital Brisbane Queensland Australia
| | - Jürgen B. Bulitta
- Department of Pharmacotherapy and Translational Research College of Pharmacy University of Florida Orlando Florida USA
| | - David L. Paterson
- The University of Queensland Centre for Clinical Research Royal Brisbane and Women’s Hospital Brisbane Queensland Australia
| | - Jeffrey Lipman
- The University of Queensland Centre for Clinical Research Royal Brisbane and Women’s Hospital Brisbane Queensland Australia
| | - Roger L. Nation
- Drug Delivery, Disposition, and Dynamics Monash Institute of Pharmaceutical SciencesMonash University Parkville Victoria Australia
| | - Jason A. Roberts
- The University of Queensland Centre for Clinical Research Royal Brisbane and Women’s Hospital Brisbane Queensland Australia
| | - Cornelia B. Landersdorfer
- Centre for Medicine Use and Safety Monash Institute of Pharmaceutical Sciences Monash University Parkville Victoria Australia
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Clinically Relevant Epithelial Lining Fluid Concentrations of Meropenem with Ciprofloxacin Provide Synergistic Killing and Resistance Suppression of Hypermutable Pseudomonas aeruginosa in a Dynamic Biofilm Model. Antimicrob Agents Chemother 2020; 64:AAC.00469-20. [PMID: 32366710 DOI: 10.1128/aac.00469-20] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/11/2020] [Accepted: 04/20/2020] [Indexed: 01/18/2023] Open
Abstract
Treatment of exacerbations of chronic Pseudomonas aeruginosa infections in patients with cystic fibrosis (CF) is highly challenging due to hypermutability, biofilm formation, and an increased risk of resistance emergence. We evaluated the impact of ciprofloxacin and meropenem as monotherapy and in combination in the dynamic in vitro CDC biofilm reactor (CBR). Two hypermutable P. aeruginosa strains, PAOΔmutS (MIC of ciprofloxacin [MICciprofloxacin], 0.25 mg/liter; MICmeropenem, 2 mg/liter) and CW44 (MICciprofloxacin, 0.5 mg/liter; MICmeropenem, 4 mg/liter), were investigated for 120 h. Concentration-time profiles achievable in epithelial lining fluid (ELF) following FDA-approved doses were simulated in the CBR. Treatments were ciprofloxacin at 0.4 g every 8 h as 1-h infusions (80% ELF penetration), meropenem at 6 g/day as a continuous infusion (CI) (30% and 60% ELF penetration), and their combinations. Counts of total and less-susceptible planktonic and biofilm bacteria and MICs were determined. Antibiotic concentrations were quantified by an ultrahigh-performance liquid chromatography photodiode array (UHPLC-PDA) assay. For both strains, all monotherapies failed, with substantial regrowth and resistance of planktonic (≥8 log10 CFU/ml) and biofilm (>8 log10 CFU/cm2) bacteria at 120 h (MICciprofloxacin, up to 8 mg/liter; MICmeropenem, up to 64 mg/liter). Both combination treatments demonstrated synergistic bacterial killing of planktonic and biofilm bacteria of both strains from ∼48 h onwards and suppressed regrowth to ≤4 log10 CFU/ml and ≤6 log10 CFU/cm2 at 120 h. Overall, both combination treatments suppressed the amplification of resistance of planktonic bacteria for both strains and of biofilm bacteria for CW44. The combination with meropenem at 60% ELF penetration also suppressed the amplification of resistance of biofilm bacteria for PAOΔmutS Thus, combination treatment demonstrated synergistic bacterial killing and resistance suppression against difficult-to-treat hypermutable P. aeruginosa strains.
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Chen F, Tang Y, Zheng H, Xu Y, Wang J, Wang C. Roles of the Conserved Amino Acid Residues in Reduced Human Defensin 5: Cysteine and Arginine Are Indispensable for Its Antibacterial Action and LPS Neutralization. ChemMedChem 2019; 14:1457-1465. [DOI: 10.1002/cmdc.201900282] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2019] [Revised: 06/21/2019] [Indexed: 01/09/2023]
Affiliation(s)
- Fang Chen
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Yong Tang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Hong Zheng
- Department of Thoracic Surgery, Xinqiao HospitalThird Military Medical University Chongqing 400037 China
| | - Yang Xu
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Junping Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
| | - Cheng Wang
- State Key Laboratory of Trauma, Burns and Combined Injury, Institute of Combined Injury of PLA, Chongqing Engineering Research Center for Nanomedicine, College of Preventive MedicineThird Military Medical University Chongqing 400038 China
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Krishnamurthy M, Lemmon MM, Falcinelli EM, Sandy RA, Dootz JN, Mott TM, Rajamani S, Schaecher KE, Duplantier AJ, Panchal RG. Enhancing the antibacterial activity of polymyxins using a nonantibiotic drug. Infect Drug Resist 2019; 12:1393-1405. [PMID: 31239720 PMCID: PMC6555264 DOI: 10.2147/idr.s196874] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 02/06/2019] [Indexed: 11/24/2022] Open
Abstract
Purpose: The rapid emergence of multidrug-resistant (MDR) bacteria and the lack of new therapies to eliminate them poses a major threat to global health. With the alarming rise in antimicrobial resistance (AMR), focus has now shifted to the use of the polymyxin class of antibiotics as the last line of defense for treatment of Gram-negative infections. Unfortunately, the growing resistance of bacteria against polymyxins is threatening the treatment of MDR infections, necessitating the need for novel strategies. The objective of this study was to determine if combination of polymyxin (polymyxin B or colistin) with a nonantibiotic small molecule AR-12, a celecoxib derivative that is devoid of cyclooxygenase 2 (COX-2) inhibitory activities, can be an effective strategy against polymyxin-resistant MDR bacteria. Methods: Growth inhibition studies, time-kill assays and permeability assays were conducted to investigate the effect of AR-12 on the antibacterial activity of polymyxins. Results: Growth studies were performed on a panel of polymyxin-resistant MDR strains using the combination of AR-12 with either colistin or polymyxin B. The combination treatment had no effect on strains that have inherent polymyxin resistance; however, AR-12 was effective in lowering the minimal inhibitory concentration (MIC) of polymyxins by 4–60-fold in several strains that had acquired polymyxin resistance. Time-kill assays using the combination of AR-12 and colistin with select MDR strains suggest rapid killing and bactericidal activity, while the permeability assays using fluorescently labeled dansylated polymyxin and 1-N-phenylnaphthylamine (NPN) in these MDR strains suggest that AR-12 can potentiate the antibacterial activity of polymyxins by possibly altering the bacterial outer membrane via modification of lipopolysaccharide and thereby improving the uptake of polymyxins. Conclusion: Our studies indicate that the combination of AR-12 and polymyxin is effective in targeting select Gram-negative bacteria that have acquired polymyxin resistance. Further understanding of the mechanism of action of AR-12 will provide new avenues for developing narrow-spectrum antibacterials to target select Gram-negative MDR bacteria. Importantly, our studies show that the use of nonantibiotic small molecules in combination with polymyxins is an attractive strategy to counter the growing resistance of bacteria to polymyxins.
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Affiliation(s)
- Malathy Krishnamurthy
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Margaret M Lemmon
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Evan M Falcinelli
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Reuel A Sandy
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Jennifer N Dootz
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Tiffany M Mott
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
| | - Sathish Rajamani
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA.,General Dynamics Information Technology, Frederick, MD, USA
| | - Kurt E Schaecher
- Department of Pathology, Walter Reed National Military Medical Center, Bethesda, MD, USA
| | - Allen J Duplantier
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA.,Cherokee Nation Assurance, Frederick, MD, USA
| | - Rekha G Panchal
- Department of Target Discovery and Experimental Microbiology, Division of Molecular and Translational Sciences, United States Army Medical Research Institute of Infectious Diseases, Frederick, MD, USA
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Bengoechea JA, Sa Pessoa J. Klebsiella pneumoniae infection biology: living to counteract host defences. FEMS Microbiol Rev 2019; 43:123-144. [PMID: 30452654 PMCID: PMC6435446 DOI: 10.1093/femsre/fuy043] [Citation(s) in RCA: 272] [Impact Index Per Article: 54.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/10/2018] [Accepted: 11/16/2018] [Indexed: 12/26/2022] Open
Abstract
Klebsiella species cause a wide range of diseases including pneumonia, urinary tract infections (UTIs), bloodstream infections and sepsis. These infections are particularly a problem among neonates, elderly and immunocompromised individuals. Klebsiella is also responsible for a significant number of community-acquired infections. A defining feature of these infections is their morbidity and mortality, and the Klebsiella strains associated with them are considered hypervirulent. The increasing isolation of multidrug-resistant strains has significantly narrowed, or in some settings completely removed, the therapeutic options for the treatment of Klebsiella infections. Not surprisingly, this pathogen has then been singled out as an 'urgent threat to human health' by several organisations. This review summarises the tremendous progress that has been made to uncover the sophisticated immune evasion strategies of K. pneumoniae. The co-evolution of Klebsiella in response to the challenge of an activated immune has made Klebsiella a formidable pathogen exploiting stealth strategies and actively suppressing innate immune defences to overcome host responses to survive in the tissues. A better understanding of Klebsiella immune evasion strategies in the context of the host-pathogen interactions is pivotal to develop new therapeutics, which can be based on antagonising the anti-immune strategies of this pathogen.
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Affiliation(s)
- José A Bengoechea
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast BT9 7BL, UK
| | - Joana Sa Pessoa
- Wellcome-Wolfson Institute for Experimental Medicine, Queen's University Belfast, Belfast BT9 7BL, UK
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Meropenem Combined with Ciprofloxacin Combats Hypermutable Pseudomonas aeruginosa from Respiratory Infections of Cystic Fibrosis Patients. Antimicrob Agents Chemother 2018; 62:AAC.01150-18. [PMID: 30104278 DOI: 10.1128/aac.01150-18] [Citation(s) in RCA: 25] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2018] [Accepted: 08/08/2018] [Indexed: 12/11/2022] Open
Abstract
Hypermutable Pseudomonas aeruginosa organisms are prevalent in chronic respiratory infections and have been associated with reduced lung function in cystic fibrosis (CF); these isolates can become resistant to all antibiotics in monotherapy. This study aimed to evaluate the time course of bacterial killing and resistance of meropenem and ciprofloxacin in combination against hypermutable and nonhypermutable P. aeruginosa Static concentration time-kill experiments over 72 h assessed meropenem and ciprofloxacin in mono- and combination therapies against PAO1 (nonhypermutable), PAOΔmutS (hypermutable), and hypermutable isolates CW8, CW35, and CW44 obtained from CF patients with chronic respiratory infections. Meropenem (1 or 2 g every 8 h [q8h] as 3-h infusions and 3 g/day as a continuous infusion) and ciprofloxacin (400 mg q8h as 1-h infusions) in monotherapies and combinations were further evaluated in an 8-day hollow-fiber infection model study (HFIM) against CW44. Concentration-time profiles in lung epithelial lining fluid reflecting the pharmacokinetics in CF patients were simulated and counts of total and resistant bacteria determined. All data were analyzed by mechanism-based modeling (MBM). In the HFIM, all monotherapies resulted in rapid regrowth with resistance at 48 h. The maximum daily doses of 6 g meropenem (T>MIC of 80% to 88%) and 1.2 g ciprofloxacin (area under the concentration-time curve over 24 h in the steady state divided by the MIC [AUC/MIC], 176), both given intermittently, in monotherapy failed to suppress regrowth and resulted in substantial emergence of resistance (≥7.6 log10 CFU/ml resistant populations). The combination of these regimens achieved synergistic killing and suppressed resistance. MBM with subpopulation and mechanistic synergy yielded unbiased and precise curve fits. Thus, the combination of 6 g/day meropenem plus ciprofloxacin holds promise for future clinical evaluation against infections by susceptible hypermutable P. aeruginosa.
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Singh AP, Prabha V, Rishi P. Synergism in dual functionality of cryptdin-2 in conjunction with antibiotics against Salmonella. Indian J Med Res 2017; 144:761-770. [PMID: 28361830 PMCID: PMC5393088 DOI: 10.4103/ijmr.ijmr_850_14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/04/2022] Open
Abstract
BACKGROUND & OBJECTIVES The emergence of multidrug-resistant Salmonella over the last two decades poses a major health risk. In this context, antimicrobial peptides have found a strategic place in the therapeutic armamentarium. Previously, we found that cryptdin-2 has the potential to augment the activity of conventional second- and third-generation anti-Salmonella antibiotics as evident by in vitro assays. In continuation to this, the present study was designed to evaluate the in vivo synergistic effects, if any, of cryptdin-2 in combination with ciprofloxacin and ceftriaxone against murine salmonellosis. METHODS Scanning electron microscopy (SEM) studies along with in vivo synergistic studies were performed using cryptdin- 2 and antibiotic combinations. In addition, peroxidative liver damage, levels of nitric oxide (NO) and antioxidant enzymes along with tumour necrosis factor-alpha (TNF-α) levels were also measured. RESULTS The SEM results revealed marked changes on the outer membrane of the bacterial cells treated with various combinations. Both the tested combinations demonstrated synergistic in vivo potency against S. Typhimurium as evident by reduction in the number of Salmonellae in the liver, spleen and intestine. Analysis of peroxidative liver damage, levels of NO and antioxidant enzymes along with TNF-α and nuclear factor-kappa B levels revealed that the tested combinations restored their levels to near normal. The most potent combination was found to be that of cryptdin-2 and ciprofloxacin in terms of direct killing and immunomodulatory potential. INTERPRETATION & CONCLUSIONS These findings suggest that cryptdin-2 may act in conjunction with conventional antibiotics indicating the possibility of developing these combinations as additional therapeutic agents to combat Salmonella infections.
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Affiliation(s)
- Aman Preet Singh
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
| | - Vijay Prabha
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
| | - Praveen Rishi
- Department of Microbiology, Basic Medical Sciences Block, Panjab University, Chandigarh, India
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Aelenei P, Miron A, Trifan A, Bujor A, Gille E, Aprotosoaie AC. Essential Oils and Their Components as Modulators of Antibiotic Activity against Gram-Negative Bacteria. MEDICINES 2016; 3:medicines3030019. [PMID: 28930130 PMCID: PMC5456245 DOI: 10.3390/medicines3030019] [Citation(s) in RCA: 34] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/30/2016] [Revised: 07/17/2016] [Accepted: 07/18/2016] [Indexed: 12/21/2022]
Abstract
Gram-negative bacteria cause infections that are difficult to treat due to the emergence of multidrug resistance. This review summarizes the current status of the studies investigating the capacity of essential oils and their components to modulate antibiotic activity against Gram-negative bacteria. Synergistic interactions are particularly discussed with reference to possible mechanisms by which essential oil constituents interact with antibiotics. Special emphasis is given to essential oils and volatile compounds that inhibit efflux pumps, thus reversing drug resistance in Gram-negative bacteria. In addition, indifference and antagonism between essential oils/volatile compounds and conventional antibiotics have also been reported. Overall, this literature review reveals that essential oils and their purified components enhance the efficacy of antibiotics against Gram-negative bacteria, being promising candidates for the development of new effective formulations against Gram-negative bacteria.
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Affiliation(s)
- Petruta Aelenei
- Department of Pharmacognosy, Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi, Universitatii 16, Iasi 700115, Romania.
- Regulatory Affairs Department, Fiterman Pharma LLC, Pacurari Road 127, Iasi 700544, Romania.
| | - Anca Miron
- Department of Pharmacognosy, Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi, Universitatii 16, Iasi 700115, Romania.
| | - Adriana Trifan
- Department of Pharmacognosy, Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi, Universitatii 16, Iasi 700115, Romania.
| | - Alexandra Bujor
- Department of Pharmacognosy, Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi, Universitatii 16, Iasi 700115, Romania.
| | - Elvira Gille
- Stejarul Biological Research Centre/National Institute of Research and Development for Biological Sciences, Alexandru cel Bun 6, Piatra Neamt 610004, Romania.
| | - Ana Clara Aprotosoaie
- Department of Pharmacognosy, Faculty of Pharmacy, University of Medicine and Pharmacy Grigore T. Popa-Iasi, Universitatii 16, Iasi 700115, Romania.
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Haemophilus influenzae induces steroid-resistant inflammatory responses in COPD. BMC Pulm Med 2015; 15:157. [PMID: 26642881 PMCID: PMC4672509 DOI: 10.1186/s12890-015-0155-3] [Citation(s) in RCA: 13] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/16/2015] [Accepted: 11/30/2015] [Indexed: 02/04/2023] Open
Abstract
Background Chronic obstructive pulmonary disease (COPD) is an inflammatory disorder partially resistant to glucocorticoids. A reduced histone deacetylase (HDAC) activity has been proposed to explain this resistance. Haemophilus influenzae frequently colonizes the airways of COPD patients, where it enhances inflammation. The effects of Haemophilus influenzae on HDAC activity have not been investigated before. Methods The effects of the presence or absence of Haemophilus influenzae ex-vivo and in vitro were studied. To this end, we determined: (1) cytokine release in alveolar macrophages (AM) from 7 patients with COPD, 5 healthy smokers, 6 healthy non-smokers and (2) HDAC activity, nuclear factor kappa B (NF-κB) activation in a macrophage-like cell line (PMA-transformed U937 cells) co-cultured with epithelial cells. Experiments were repeated with dexamethasone (1 μM) and/or the HDAC enhancer theophylline (10 μM). Results Haemophilus influenzae induced a steroid-resistant inflammatory response in AM from COPD and controls and decreased HDAC activity, activated NF-κB and induced the secretion of several cytokines (IL-6, IL-8, IL-1β, IL-10 and TNF-α) (p < 0.001 for all comparisons) in the macrophage-like cell line. Dexamethasone reduced NF-κB activation but it did not modify HDAC activity. The addition of theophylline to dexamethasone increased HDAC activity and suppressed cytokine release completely, without modifying NF-κB activation. Conclusions These results indicate that Haemophilus influenzae reduces HDAC activity and induces a NF-κB mediated inflammatory response that is only partially suppressed by glucocorticoids irrespective of having COPD. Yet, the latter can be fully restored by targeting HDAC activity. Electronic supplementary material The online version of this article (doi:10.1186/s12890-015-0155-3) contains supplementary material, which is available to authorized users.
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Antimicrobial Effects and Resistant Regulation of Magnolol and Honokiol on Methicillin-Resistant Staphylococcus aureus. BIOMED RESEARCH INTERNATIONAL 2015; 2015:283630. [PMID: 26357651 PMCID: PMC4556871 DOI: 10.1155/2015/283630] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 06/03/2015] [Accepted: 08/06/2015] [Indexed: 11/17/2022]
Abstract
The antimicrobial killing activity toward methicillin-resistant Staphylococcus aureus (MRSA) has been a serious emerging global issue. In a continuing search for compounds with antibacterial activity against several microorganisms including S. aureus and MRSA, an n-hexane extract of Magnolia officinalis was found to contain magnolol. This compound exhibited potent activity against S. aureus, standard methicillin-susceptible S. aureus (MSSA), and MRSA as well as clinical MRSA isolates. When combined with oxacillin, the antibacterial activities of magnolol and honokiol against the MRSA strain were increased compared to single treatment without antibiotics at 10 µg/mL and 25 µg/mL, respectively. These activities of magnolol and honokiol were dose dependent. Also, magnolol showed synergistic effects with oxacillin against 13 clinical isolates of MRSA. It was determined that magnolol and honokiol had a synergistic effect with oxacillin against MRSA strain. Furthermore, the magnolol inhibited the expression of the resistant genes, mecA, mecI, femA, and femB, in mRNA. We concluded that the antibacterial activity of magnolol against MRSA strain is more related to the mecI's pathway and components of the cell wall than mecR1. Therefore, the results obtained in this study suggest that the combination of magnolol and antibiotics could lead to the development of new combination antibiotics against MRSA infection.
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Dougherty K, Smith BA, Moore AF, Maitland S, Fanger C, Murillo R, Baltrus DA. Multiple phenotypic changes associated with large-scale horizontal gene transfer. PLoS One 2014; 9:e102170. [PMID: 25048697 PMCID: PMC4105467 DOI: 10.1371/journal.pone.0102170] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/09/2014] [Accepted: 06/16/2014] [Indexed: 12/22/2022] Open
Abstract
Horizontal gene transfer often leads to phenotypic changes within recipient organisms independent of any immediate evolutionary benefits. While secondary phenotypic effects of horizontal transfer (i.e., changes in growth rates) have been demonstrated and studied across a variety of systems using relatively small plasmids and phage, little is known about the magnitude or number of such costs after the transfer of larger regions. Here we describe numerous phenotypic changes that occur after a large-scale horizontal transfer event (∼1 Mb megaplasmid) within Pseudomonas stutzeri including sensitization to various stresses as well as changes in bacterial behavior. These results highlight the power of horizontal transfer to shift pleiotropic relationships and cellular networks within bacterial genomes. They also provide an important context for how secondary effects of transfer can bias evolutionary trajectories and interactions between species. Lastly, these results and system provide a foundation to investigate evolutionary consequences in real time as newly acquired regions are ameliorated and integrated into new genomic contexts.
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Affiliation(s)
- Kevin Dougherty
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - Brian A. Smith
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - Autumn F. Moore
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - Shannon Maitland
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - Chris Fanger
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - Rachel Murillo
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
| | - David A. Baltrus
- School of Plant Sciences, University of Arizona, Tucson, Arizona, United States of America
- * E-mail:
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A dual mechanism involved in membrane and nucleic acid disruption of AvBD103b, a new avian defensin from the king penguin, against Salmonella enteritidis CVCC3377. Appl Microbiol Biotechnol 2014; 98:8313-25. [PMID: 24981062 DOI: 10.1007/s00253-014-5898-x] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/02/2014] [Revised: 06/09/2014] [Accepted: 06/11/2014] [Indexed: 02/07/2023]
Abstract
The food-borne bacterial gastrointestinal infection is a serious public health threat. Defensins are evolutionarily conserved innate immune components with broad-spectrum antibacterial activity that do not easily induce resistance. AvBD103b, an avian defensin with potent activity against Salmonella enteritidis, was isolated from the stomach contents of the king penguin (Aptenodytes patagonicus). To elucidate further the antibacterial mechanism of AvBD103b, its effect on the S. enteritidis CVCC3377 cell membrane and intracellular DNA was researched. The cell surface hydrophobicity and a N-phenyl-1-naphthylamine uptake assay demonstrated that AvBD103b treatment increased the cell surface hydrophobicity and outer membrane permeability. Atomic absorption spectrometry, ultraviolet spectrophotometry, flow cytometry, and transmission electron microscopy (TEM) indicated that AvBD103b treatment can lead to the release of the cellular contents and cell death through damage of the membrane. DNA gel retardation and circular dichroism analysis demonstrated that AvBD103b interacted with DNA and intercalated into the DNA base pairs. A cell cycle assay demonstrated that AvBD103b affected cellular functions, such as DNA synthesis. Our results confirmed that AvBD103b exerts its antibacterial activity by damaging the cell membrane and interfering with intracellular DNA, ultimately causing cell death, and suggested that AvBD103b may be a promising candidate as an alternative to antibiotics against S. enteritidis.
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15
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Bacteriostatic antimicrobial combination: antagonistic interaction between epsilon-viniferin and vancomycin against methicillin-resistant Staphylococcus aureus. BIOMED RESEARCH INTERNATIONAL 2014; 2014:461756. [PMID: 24783205 PMCID: PMC3982270 DOI: 10.1155/2014/461756] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 11/15/2013] [Accepted: 02/25/2014] [Indexed: 01/23/2023]
Abstract
Stilbenoids have been considered as an alternative phytotherapeutic treatment against methicillin-resistant Staphylococcus aureus (MRSA) infection. The combined effect of ε-viniferin and johorenol A with the standard antibiotics, vancomycin and linezolid, was assessed against MRSA ATCC 33591 and HUKM clinical isolate. The minimum inhibitory concentration (MIC) value of the individual tested compounds and the fractional inhibitory concentration index (FICI) value of the combined agents were, respectively, determined using microbroth dilution test and microdilution checkerboard (MDC) method. Only synergistic outcome from checkerboard test will be substantiated for its rate of bacterial killing using time-kill assay. The MIC value of ε-viniferin against ATCC 33591 and johorenol A against both strains was 0.05 mg/mL whereas HUKM strain was susceptible to 0.1 mg/mL of ε-viniferin. MDC study showed that only combination between ε-viniferin and vancomycin was synergistic against ATCC 33591 (FICI 0.25) and HUKM (FICI 0.19). All the other combinations (ε-viniferin-linezolid, johorenol A-vancomycin, and johorenol A-linezolid) were either indifferent or additive against both strains. However, despite the FICI value showing synergistic effect for ε-viniferin-vancomycin, TKA analysis displayed antagonistic interaction with bacteriostatic action against both strains. As conclusion, ε-viniferin can be considered as a bacteriostatic stilbenoid as it antagonized the bactericidal activity of vancomycin. These findings therefore disputed previous report that ε-viniferin acted in synergism with vancomycin but revealed that it targets similar site in close proximity to vancomycin's action, possibly at the bacterial membrane protein. Hence, this combination has a huge potential to be further studied and developed as an alternative treatment in combating MRSA in future.
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16
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Efficacy of cryptdin-2 as an adjunct to antibiotics from various generations against salmonella. Indian J Microbiol 2014; 54:323-8. [PMID: 24891740 DOI: 10.1007/s12088-014-0463-y] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/31/2013] [Accepted: 03/05/2014] [Indexed: 12/13/2022] Open
Abstract
Emerging drug resistance in Salmonella coupled with the recent poor success rate of antibiotic discovery programs of the pharmaceutical industry is a cause for significant concern. It has forced the scientific community to look for alternative new classes of antimicrobial compounds. In this context, combinations of antimicrobial peptides (AMPs) and conventional antibiotics have gained interest owing to their versatile applications. The present study was therefore planned to evaluate the synergistic effects, if any, of cryptdin-2, a mouse Paneth cell alpha-defensin, in combination with four different antibiotics i.e. ciprofloxacin, ceftriaxone, cefotaxime and chloramphenicol, which are conventionally used against Salmonella. Minimum bactericidal concentrations of the selected antimicrobial agents were determined by micro and macro broth dilution assays. In-vitro synergy between the agents was evaluated by fractional bactericidal concentration index (checkerboard test) and time-kill assay. Cryptdin-2-ciprofloxacin, cryptdin-2-ceftriaxone and cryptdin-2-cefotaxime combinations were found synergistic as evident by in vitro assays. This synergism provides an additional therapeutic choice by allowing the use of conventional antibiotics in conjunction with AMPs against MDR Salmonella.
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Velkov T, Deris ZZ, Huang JX, Azad MAK, Butler M, Sivanesan S, Kaminskas LM, Dong YD, Boyd B, Baker MA, Cooper MA, Nation RL, Li J. Surface changes and polymyxin interactions with a resistant strain of Klebsiella pneumoniae. Innate Immun 2013; 20:350-63. [PMID: 23887184 DOI: 10.1177/1753425913493337] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022] Open
Abstract
This study examines the interaction of polymyxin B and colistin with the surface and outer membrane components of a susceptible and resistant strain of Klebsiella pneumoniae. The interaction between polymyxins and bacterial membrane and isolated LPS from paired wild type and polymyxin-resistant strains of K. pneumoniae were examined with N-phenyl-1-naphthylamine (NPN) uptake, fluorometric binding and thermal shift assays, lysozyme and deoxycholate sensitivity assays, and by (1)H NMR. LPS from the polymyxin-resistant strain displayed a reduced binding affinity for polymyxins B and colistin in comparison with the wild type LPS. The outer membrane NPN permeability of the resistant strain was greater compared with the susceptible strain. Polymyxin exposure enhanced the permeability of the outer membrane of the wild type strain to lysozyme and deoxycholate, whereas polymyxin concentrations up to 32 mg/ml failed to permeabilize the outer membrane of the resistant strain. Zeta potential measurements revealed that mid-logarithmic phase wild type cells exhibited a greater negative charge than the mid-logarithmic phase-resistant cells. Taken together, our findings suggest that the resistant derivative of K. pneumoniae can block the electrostatically driven first stage of polymyxin action, which thereby renders the hydrophobically driven second tier of polymyxin action on the outer membrane inconsequential.
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Affiliation(s)
- Tony Velkov
- 1Drug Development and Innovation, Drug Delivery, Disposition and Dynamics, Monash Institute of Pharmaceutical Sciences, Monash University, Parkville, VIC, Australia
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18
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Singh AP, Preet S, Rishi P. Augmentation of antimicrobial activity of conventional antibiotics by cell-free extract of L. plantarum. J Antibiot (Tokyo) 2011; 64:795-8. [PMID: 22008700 DOI: 10.1038/ja.2011.92] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023]
Affiliation(s)
- Aman Preet Singh
- Department of Microbiology, Basic Medical Sciences Building, Panjab University, Chandigarh, India
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19
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Hemaiswarya S, Doble M. Synergistic interaction of phenylpropanoids with antibiotics against bacteria. J Med Microbiol 2010; 59:1469-1476. [DOI: 10.1099/jmm.0.022426-0] [Citation(s) in RCA: 65] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/18/2022] Open
Abstract
Phenylpropanoids constitute a large part of our daily diet and there is a possibility that they might interact with synthetic drugs. The present work was aimed at studying the interaction of seven phenylpropanoids (cinnamic, p-coumaric, caffeic, chlorogenic, ferulic, 3,4-dimethoxycinnamic and 2,4,5-trimethoxycinnamic acid) with five antibiotics (amikacin, ampicillin, ciprofloxacin, erythromycin and vancomycin) against Gram-negative (Escherichia coli, Enterobacter aerogenes and Pseudomonas aeruginosa) and Gram-positive (Staphylococcus aureus) bacteria. The interaction studies were performed by chequerboard and time–kill curve assays. Both assays revealed that cinnamic, p-coumaric and ferulic acids were the most active. They combined synergistically with the majority of the antibiotics and exhibited enhanced activity against all the micro-organisms. The time–kill curve parameters were better (P<0.05) for the combinations of amikacin with ferulic, cinnamic or p-coumaric acid than for the individual treatments. Amikacin was the most favourable antibiotic and S. aureus was the most sensitive microbe to most of the combinations. These phenylpropanoids damaged the bacterial membrane as assessed by the LIVE/DEAD
BacLight kit, and structure–activity relationship studies indicated that hydrophilic groups enhanced this activity.
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Affiliation(s)
- Shanmugam Hemaiswarya
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
| | - Mukesh Doble
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
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20
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Design, synthesis, and evaluation of a new fluorescent probe for measuring polymyxin-lipopolysaccharide binding interactions. Anal Biochem 2010; 409:273-83. [PMID: 21050838 DOI: 10.1016/j.ab.2010.10.033] [Citation(s) in RCA: 43] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2010] [Revised: 10/27/2010] [Accepted: 10/27/2010] [Indexed: 11/24/2022]
Abstract
Fluorescence assays employing semisynthetic or commercial dansyl-polymyxin B have been widely employed to assess the affinity of polycations, including polymyxins, for bacterial cells and lipopolysaccharide (LPS). The five primary γ-amines on diaminobutyric acid residues of polymyxin B are potentially derivatized with dansyl-chloride. Mass spectrometric analysis of the commercial product revealed a complex mixture of di- or tetra-dansyl-substituted polymyxin B. We synthesized a mono-substituted fluorescent derivative, dansyl[Lys]¹polymyxin B₃. The affinity of polymyxin for purified gram-negative LPS and whole bacterial cells was investigated. The affinity of dansyl[Lys]¹polymyxin B₃ for LPS was comparable to polymyxin B and colistin, and considerably greater (K(d)<1 μM) than for whole cells (K(d)∼6-12μM). Isothermal titration calorimetric studies demonstrated exothermic enthalpically driven binding between both polymyxin B and dansyl[Lys]¹polymyxin B₃ to LPS, attributed to electrostatic interactions. The hydrophobic dansyl moiety imparted a greater entropic contribution to the dansyl[Lys]¹polymyxin B₃-LPS reaction. Molecular modeling revealed a loss of electrostatic contact within the dansyl[Lys]¹polymyxin B₃-LPS complex due to steric hindrance from the dansyl[Lys]¹ fluorophore; this corresponded with diminished antibacterial activity (MIC≥16μg/mL). Dansyl[Lys]¹polymyxin B₃ may prove useful as a screening tool for drug development.
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21
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Structural features governing the activity of lactoferricin-derived peptides that act in synergy with antibiotics against Pseudomonas aeruginosa in vitro and in vivo. Antimicrob Agents Chemother 2010; 55:218-28. [PMID: 20956602 DOI: 10.1128/aac.00904-10] [Citation(s) in RCA: 42] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
Pseudomonas aeruginosa is naturally resistant to many antibiotics, and infections caused by this organism are a serious threat, especially to hospitalized patients. The intrinsic low permeability of P. aeruginosa to antibiotics results from the coordinated action of several mechanisms, such as the presence of restrictive porins and the expression of multidrug efflux pump systems. Our goal was to develop antimicrobial peptides with an improved bacterial membrane-permeabilizing ability, so that they enhance the antibacterial activity of antibiotics. We carried out a structure activity relationship analysis to investigate the parameters that govern the permeabilizing activity of short (8- to 12-amino-acid) lactoferricin-derived peptides. We used a new class of constitutional and sequence-dependent descriptors called PEDES (peptide descriptors from sequence) that allowed us to predict (Spearman's ρ = 0.74; P < 0.001) the permeabilizing activity of a new peptide generation. To study if peptide-mediated permeabilization could neutralize antibiotic resistance mechanisms, the most potent peptides were combined with antibiotics, and the antimicrobial activities of the combinations were determined on P. aeruginosa strains whose mechanisms of resistance to those antibiotics had been previously characterized. A subinhibitory concentration of compound P2-15 or P2-27 sensitized P. aeruginosa to most classes of antibiotics tested and counteracted several mechanisms of antibiotic resistance, including loss of the OprD porin and overexpression of several multidrug efflux pump systems. Using a mouse model of lethal infection, we demonstrated that whereas P2-15 and erythromycin were unable to protect mice when administered separately, concomitant administration of the compounds afforded long-lasting protection to one-third of the animals.
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22
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Oo TZ, Cole N, Garthwaite L, Willcox MDP, Zhu H. Evaluation of synergistic activity of bovine lactoferricin with antibiotics in corneal infection. J Antimicrob Chemother 2010; 65:1243-51. [DOI: 10.1093/jac/dkq106] [Citation(s) in RCA: 58] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022] Open
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23
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Hemaiswarya S, Doble M. Synergistic interaction of eugenol with antibiotics against Gram negative bacteria. PHYTOMEDICINE : INTERNATIONAL JOURNAL OF PHYTOTHERAPY AND PHYTOPHARMACOLOGY 2009; 16:997-1005. [PMID: 19540744 DOI: 10.1016/j.phymed.2009.04.006] [Citation(s) in RCA: 139] [Impact Index Per Article: 9.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 02/01/2009] [Revised: 03/26/2009] [Accepted: 04/24/2009] [Indexed: 05/21/2023]
Abstract
Eugenol, the principal chemical component of clove oil from Eugenia aromatica has been long known for its analgesic, local anesthetic, anti-inflammatory, and antibacterial effects. The interaction of the eugenol with ten different hydrophobic and hydrophilic antibiotics was studied against five different Gram negative bacteria. The MIC of the combination was found to decrease by a factor of 5-1000 with respect to their individual MIC. This synergy is because of the membrane damaging nature of eugenol, where 1mM of its concentration is able to damage nearly 50% of the bacterial membrane. Eugenol was also able to enhance the activities of lysozyme, Triton X-100 and SDS in damaging the bacterial cell membrane. The hydrophilic antibiotics such as vancomycin and beta-lactam antibiotics which have a marginal activity on these gram negative bacteria exhibit an enhanced antibacterial activity when pretreated with eugenol. Reduced usage of antibiotics could be employed as a treatment strategy to slow down the onset of antibiotic resistance as well as decrease its toxicity. Experiments performed with human blood cells indicated that the concentration of eugenol used for the combination studies were below its cytotoxic values. Pharmacodynamic studies of the combinations need to be performed to decide on the effective dosage.
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Affiliation(s)
- S Hemaiswarya
- Department of Biotechnology, Indian Institute of Technology Madras, Chennai 600 036, India
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24
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Llobet E, Tomás JM, Bengoechea JA. Capsule polysaccharide is a bacterial decoy for antimicrobial peptides. MICROBIOLOGY-SGM 2009; 154:3877-3886. [PMID: 19047754 DOI: 10.1099/mic.0.2008/022301-0] [Citation(s) in RCA: 203] [Impact Index Per Article: 13.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/18/2022]
Abstract
Antimicrobial peptides (APs) are important host weapons against infections. Nearly all APs are cationic and their microbicidal action is initiated through interactions with the anionic bacterial surface. It is known that pathogens have developed countermeasures to resist these agents by reducing the negative charge of membranes, by active efflux and by proteolytic degradation. Here we uncover a new strategy of resistance based on the neutralization of the bactericidal activity of APs by anionic bacterial capsule polysaccharide (CPS). Purified CPSs from Klebsiella pneumoniae K2, Streptococcus pneumoniae serotype 3 and Pseudomonas aeruginosa increased the resistance to polymyxin B of an unencapsulated K. pneumoniae mutant. Furthermore, these CPSs increased the MICs of polymyxin B and human neutrophil alpha-defensin 1 (HNP-1) for unencapsulated K. pneumoniae, Escherichia coli and P. aeruginosa PAO1. Polymyxin B or HNP-1 released CPS from capsulated K. pneumoniae, S. pneumoniae serotype 3 and P. aeruginosa overexpressing CPS. Moreover, this material also reduced the bactericidal activity of APs. We postulate that APs may trigger in vivo the release of CPS, which in turn will protect bacteria against APs. We found that anionic CPSs, but not cationic or uncharged ones, blocked the bactericidal activity of APs by binding them, thereby reducing the amount of peptides reaching the bacterial surface. Supporting this, polycations inhibited such interaction and the bactericidal activity was restored. We postulate that trapping of APs by anionic CPSs is an additional selective virulence trait of these molecules, which could be considered as bacterial decoys for APs.
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Affiliation(s)
- Enrique Llobet
- Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Program Infection and Immunity, Fundació Caubet-CIMERA Illes Balears, Bunyola, Spain
| | - Juan M Tomás
- Departamento de Microbiología, Facultad de Biología, Universidad de Barcelona, Barcelona, Spain
| | - Jose A Bengoechea
- Área de Microbiología, Facultad Biología, Universitat Illes Balears, Palma Mallorca, Spain.,Centro de Investigación Biomédica en Red de Enfermedades Respiratorias (CIBERES), Bunyola, Spain.,Program Infection and Immunity, Fundació Caubet-CIMERA Illes Balears, Bunyola, Spain
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25
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Klebsiella pneumoniae OmpA confers resistance to antimicrobial peptides. Antimicrob Agents Chemother 2008; 53:298-302. [PMID: 19015361 DOI: 10.1128/aac.00657-08] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
A Klebsiella pneumoniae ompA mutant was more susceptible to antimicrobial peptides (APs) than the wild type. Susceptibility did not result from surface changes other than the absence of OmpA. Our data suggest that OmpA is implicated in the activation of yet-unknown systems dedicated to ameliorating AP cytotoxicity.
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26
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The plasmid-encoded regulator activates factors conferring lysozyme resistance on enteropathogenic Escherichia coli strains. Appl Environ Microbiol 2008; 75:275-80. [PMID: 18997020 DOI: 10.1128/aem.01734-08] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022] Open
Abstract
We demonstrate that enhanced lysozyme resistance of enteropathogenic Escherichia coli requires the plasmid-encoded regulator, Per, and is mediated by factors outside the locus for enterocyte effacement. EspC, a Per-activated serine protease autotransporter protein, conferred enhanced resistance on nonpathogenic E. coli, and a second Per-regulated, espC-independent lysozyme resistance mechanism was identified.
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27
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Skurnik M, Biedzka-Sarek M, Lübeck PS, Blom T, Bengoechea JA, Pérez-Gutiérrez C, Ahrens P, Hoorfar J. Characterization and biological role of the O-polysaccharide gene cluster of Yersinia enterocolitica serotype O:9. J Bacteriol 2007; 189:7244-53. [PMID: 17693522 PMCID: PMC2168460 DOI: 10.1128/jb.00605-07] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/19/2007] [Accepted: 07/16/2007] [Indexed: 11/20/2022] Open
Abstract
Yersinia enterocolitica serotype O:9 is a gram-negative enteropathogen that infects animals and humans. The role of lipopolysaccharide (LPS) in Y. enterocolitica O:9 pathogenesis, however, remains unclear. The O:9 LPS consists of lipid A to which is linked the inner core oligosaccharide, serving as an attachment site for both the outer core (OC) hexasaccharide and the O-polysaccharide (OPS; a homopolymer of N-formylperosamine). In this work, we cloned the OPS gene cluster of O:9 and identified 12 genes organized into four operons upstream of the gnd gene. Ten genes were predicted to encode glycosyltransferases, the ATP-binding cassette polysaccharide translocators, or enzymes required for the biosynthesis of GDP-N-formylperosamine. The two remaining genes within the OPS gene cluster, galF and galU, were not ascribed a clear function in OPS biosynthesis; however, the latter gene appeared to be essential for O:9. The biological functions of O:9 OPS and OC were studied using isogenic mutants lacking one or both of these LPS parts. We showed that OPS and OC confer resistance to human complement and polymyxin B; the OPS effect on polymyxin B resistance could be observed only in the absence of OC.
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Affiliation(s)
- Mikael Skurnik
- Department of Bacteriology and Immunology, Haartman Institute, University of Helsinki, Finland.
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